Self-stepping reversible relay chain



May 3, 1960 G. D. PERKINS SELF-STEPPING REVERSIBLE RELAY CHAIN FiledJuly 5, 1955 United States Patent C v 2,935,658 sELii-srEPPINGREVERSIBLE RELAY CHAIN George D. Perkins, Duarte, Calif., assigner, bymesne assignments, to Bell & Howell Company, Chicago, Ill., acorporation of Illinois Application July `5, 1955,.Serial No. 519,776

7 Claims. (Cl. 317-140) This invention relates to aself-stepping relaychain in which the relays operate insuccessionin response to onecondition of operation and in which the relays release in reversesuccession in response to another condition of operation.

Sequential operation of a stepping switch or of a relay chain isrequired in many circuits, such as those employed in data handling or incontrol apparatus. Stepping switches are ordinarily employed to providesuch operation, but they are subject to the disadvantage of relativelyslow operation and they wear out more rapidly than relays due to therelatively complex mechanical action which -is required in a steppingswitch. In some instances relay chains have been employed to provide astepping action, but such arrangements are ordinarily of complex designand cumbersome.

In accordance with the present` invention, a simplified self-steppingreversible relay chain is provided by ernploying the contacts of therespective relays to energize the relay windings in sequence and causerelays to operate in succession, by employing resistance in the circuitsfor holding the respective relays, with the resistance beingproportioned to provide a holding current which is slightly greater thanthe minimum required for the respective relays, and by applying areverse current through the respective relay windings Vin reversesequence in order to cause the relays to release in reverse succession.

The invention is explained in detailwith reference to the single figureof the drawing.

The relay chain comprises a plurality of relays 19 to 14., Each of therelays 10 to 14 comprises a step in the relay chain. Each of the relays10 to 14 has a single winding` for operating the relay. Each relayexcept the first and the last in the chain has first and second sets ofcontacts which are open and third and fourth sets of contacts which areclosed when the relay is in a released condition, with eachset ofcontacts having one movable contact and one fixed contact. The secondset of contacts is employed in the holding circuits for the respectiverelays, and it is desirable that the second set of contacts close beforethe third set of contacts open when the relay changes from aV releasedto an operated condition. The first relay 10 of the chain has the first,second and third sets of contacts and the last relay 14 of the chain hasthe second, third and fourth sets of contacts.

A first source of potential 16 and a second source of potential 18provide current for operating and releasing the relays. Current from thesource of potential 16 is applied to the relay chain through a switch 20and the relays operate in succession from left to right when the switchis closed. The source of potential 18 is applied to the relay chain by aswitch 22, and the relays release in reverse order from right to leftupon closure of the switch 22. Only one of the switches 20 and 22 shouldbe closed at one time.

The winding of the Erst relay 10 of the chain is con- ICC 2 nectedthrough its third set of contacts to the switch 20. The windings of theother relays are connected to the switch 20 through the third set ofcontacts of the respective relays and the rst set of contacts of thenext preceding relay in the chain.

Resistors 24 are connected between the movable contact of the second setof contacts of each relay and the negative terminal of the source ofpotential 16 to provide a holding current for causing the respectiverelays to remain in an operated condition until they are released by areverse current from the source of potential 18. The resistors 24 areproportioned to provide a holding current which is slightly greater thantheminimum holding current required for the individual relays. Thisprovides reliable holding action, yet the low holding current makes iteasy to release the relays by applying a reverse current through theirwindings. That is, the low holding current permits faster releasingaction on the part of the relays'. v

Resistors 26 are coupled between the movable contact of the second setof contacts and one contact of the fourth set of contacts of thesuccessive pairs of relays from left to right and between the movablecontact of the second set of contacts of the last relay of the chain andthe switch 22. The resistors 25 and the associated relay contacts areconnected between. the serially connected source of potential 18 andswitch 22 and the windings of the respective relays to provide a reversecurrent through the relay windings which causes them to release when theswitch 22 is closed. The resistors are proportioned to provide thedesired reverse current.

Depending upon the direction in which the relay chain is to step, eitherthe switch 2'0 or the switch 22 is closed to initiate the desiredstepping action. The switch remains 'closed until the desiredfnumber ofsteps have been eiected, and then it is opened to cause the relays whichare then in an operated condition Vto remain in that condition.

Y If all of the relays are in a released condition as illustrated in thedrawing, the rst ltwo relays maybe operated by closing the switch 20longenough to permit current to ow through the third vset of contacts ofthe first relay- 10 to operate the first relay and through the first setof contacts of the operated first relay and the third set of contacts ofthe second relay 11 to operate the second relay. The relays. 10 and 11are held in an operated condition by the second set of contacts of eachof these two relays and by the resistors 24 which are connected betweenthese sets of contacts -andthe negative terminal of the source ofpotential 16.

In order to cause the two relays 10 and 11 to step in the reversedirection, the switch 22 is closed. This causes a current from thesourceof potential 18 to ow through the fourth set of contacts of the relay12, and through the resistor 26 and the second set of contacts of therelay 11 to provide a reverse current through the winding of the relay.This causes the relay 11 to release, and then a reverse current isapplied through the fourth set of contacts of the relay 11, the resistor26, and the second set of contacts of the relay 10 to the winding of therelay 10 to cause this relay Vto release.

Ordinarily the sources of potential 16 and 18 are direct currentsources. However, they may provide pulse signals. Such pulse signalswill cause theapparatus to function in the same manner as describedabove provided the duration of each of the pulses is equal to or largerthan the time required for one of the relays to operate. 1

The relay chain may be employed to perform various functions. Asillustrated in the drawing, a fifth set of contacts may be provided onthe respective relays, and

th'esecontactsmaybeemployed to connect or disconnect individual -inputcircuits to a common line or load 2S.

In one embodiment of the invention, the following circuit constants Wereemployed:

Withv such an arrangement the respective relays required approximatelyeight milliseconds per relay to operate upon' closure of the switch 20,and the respective relays required approximately three milliseconds perrelay to release upon closure of the switch 22.

The speed at which the Yrelays operate and release is determined by.-.the characteristics of the relays, the voltage offthe sources ofpotential, and the values of the resistors 24 and 26. I

The resistors 24 and 26 which are employed in conjunction with therespective relays serve the dual functions of `,decreasing the timerequired to release the respective relays and decreasing the amount ofpower required Lto operate the relay chain.

Although the mechanical switches 20 and 22 have been illustrated in,thedrawings, it will be apparent that any desired switching arrangementmay be employed for applying the Sources of potential to the relaychain. By way of example, an electronic switching arrangement may beemployed if desired.

The five relay chain shown in the drawings is merely illustrative andany desired number of relays may be employed.

I claim:

1. A self-stepping reversible relay chain comprising a pluralityofzrelays with each relay having a single winding for operating therelay and having a plurality of sets of contacts which are actuated byoperation and release of the relay, means including contacts of therelays for energizing the respective relay windings in succession sothat the relays operate in successive steps, means including a resistorfor each relay providing a circuitffor holding the respective relays inan operated condition, with each resistor being proportioned to providea holding current which is slightly greater than the minimum requiredfortheA respective relays, and means including contacts of the relaysfor applying a reverse current through the respective relay windings inreverse succession to cause the relays to release in reverse succession.

2. A self-stepping reversible relay chain comprising a t plurality ofrelays with each relay having a single winding for operatingthe relayand having a plurality of sets of contacts which are actuated byoperation and release of the relay, means including contacts of therelays for energizing the respective relay windings in succession sethat the relays operate in successive steps, means providing a circuitfor holding the respective relays in an operated condition, and meansincluding contacts of the rela-ys for applying a reverse current throughthe respective relay windings in reverse succession to cause the relaysto release in reverse succession.

3. A self-stepping reversible relay chain comprising a plurality ofrelays With eachl relay having a Winding for operating the relay andhaving a plurality of sets of contacts which are actuated by operationand release of the relay, first and second sources of potential, firstswitching means coupled between the first source of potential and therelay windings for energizing the respective relay windings insuccessionso that the relays operate in successive steps when the 'first switchingmeans is actuated, first resistance means coupled between a set ofcontacts of each relay and the first source of potential for holding therespective relays in an operated condition after they have been:energized with current from the first source of potential, and secondswitching means and second Vresistance means coupled between the secondsource of potential and the relay windings for applying a -reversecurrent through the respective relay windings in reverse succession whenthe second switching means is actuated so that the relays release inreverse succession.

4. A self-stepping reversible relay chain comprising a plurality ofrelays with each'V relay having a winding for operating the relay, eachrelay except the first and the last in thechain having first and secondsets of contacts which are open and third and fourth sets of contactswhich are 'closed when theV relay is released, the first relay of thechain having the first, second and third sets of contacts, and the lastrelay of the chain having the second, third' and fourth sets ofcontacts, firstl and second sources of potential, switching meansincluding the first and third sets of contacts coupled between the firstsource of potential and the relay windings for energizing the respectiverelay windings in succession so that the relays operate lin successivesteps, and switching means including the'second and fourth sets ofcontacts coupled between the second source of potential and the relaywindings for applying current through the respective 'relay windings inreverse succession, with the current from the second source of potentialflowing in the QPPOSite direction to that provided by the first sourceAof potential so that the relays release'in reverse succession.

5. A self-stepping reversible relay chain comprising a plurality ofrelays with each relay having a winding for operating the relay, eachrelay except the first and the last in the chain having first and secondsets of contacts which are open and third and fourth sets of contactswhich are closed when the relay is released, the first relay of thechain having the first, second and third sets of contacts, and the lastrelay of the chain having the second, third and fourth sets of contacts,a first source of potential, a second source of potential, meansconnecting the winding of the first' relay of the chain through itsthird set of contacts to the first source of potential, means connectingthe windings ofthe other relays to the first source of potential throughthe third set of contacts ofY the respective relays and the first set ofcontacts of the,

next preceding relay in the chain, first resistance means coupledbetween the second set of contacts of each relay and the first source ofpotential for holding the respective relays in an operated conditionafter they have been energized with current from the first source ofpotential, second resistance means coupled between the second and fourthsets of contacts of the successive pairs of relays and between thesecond set of contacts of the last relay of the chain and the secondsource of potential, and means including the fourth sets of contacts ofthe relays and the second resistance means coupled between the secondsource of potential and the relay windings for applying a reversecurrent through the respective relay windings in reverse succession, sothat the relays operate 1n succession in response to current from thefirst source of potential and release in reverse succession in responseto current from the second source.

6. A self-stepping reversible relay' chain comprising a plurality ofrelays with each relay having a winding for operating thel relay, eachrelay except the first and t'ne last in the chain having first andsecond sets of contacts which are open and -third and fourth sets ofcontacts which are closed when the 'relay is released, with the secondset of contacts closing before the third set of contacts open when therelay changes Vfrom a released to an operated condition, the first relay.of Ithe chain having the first, second and third sets of contacts, andthe last relay of. the chain having the second, third and fourth sets ofcontacts, a first source of potential having a first switch connected inserieswith it, a second source of potential having a second switchconnected in series with it, means connecting the winding of the flrstrelay'l of the chain through its third set of contacts to the vseriallyconnected,

first source of potential andfirst switch, means connecting the windingsof the other relays to the serially connected rst source of potentialand irst switch through the third set of contacts of the respectiverelays and the rst set of contacts of the next preceding relay in thechain, first resistance means coupled` between the second set ofcontacts of each relay and the first source of potential for holding therespective relays in an operated condition after they have beenenergized with current from the rst source of potential, secondresistance means coupled betweenthe second and fourth sets of contactsof the successive pairs of relays and between the second set of contactsof the last relay of the chain and the serially connected second sourceof potential and second switch, and means including the fourth sets ofcontacts of the relays and the second resistance means coupled betweenthe serially connected second source of potential and second switch andthe relay windings for applying a reverse current through the respectiverelay windings in reverse succession when the second switch is closed,so that the relays operate in succession when the first switch is closedVand release in reverse succession when the second switchY is closed. v

7. A self-stepping reversible relay chain comprising a plurality ofrelays with each relay having a winding for operating the relay, eachrelay except the first and-the last in the chain having first and secondsets of contacts which are open and third and fourth sets of contactswhich are closed when the relay is released, with each set of coni 6series with it, means connecting the winding of the irst relay of thechain through its third set of contacts to the Vserially connected firstsource of potential and tirst switch,

means connecting the windings of the other relays to the seriallyconnected irst source of potential and first switch through the thirdset of contacts of the respective relays and the tirst set of contactsof the next preceding relay in the chain, rst resistance means coupledbetween the movable contact of the second set of contacts of each relayand the first source of potential for holding the respective relays inan operated condition after they have been energized with current fromthe irst source of potential, second resistance means coupled betweenthe movable contact of the second set of contacts and one contact of thefourth set of contacts of the successive pairs of relays and between themovable contact of the second set of contacts of the last relay of thechain and the serially connected second sourceV of potential and secondReferences Cited in the tile of this patent Y UNITED STATES PATENTS1,838,961

Robinson Dec. 29, 1931 2,008,909 Hershey July 23, 1935 Y2,140,601Serriere Dec. 20, 1938 ,2,236,276 Stewart Mar. 25, 1941 Y2,593,578Liberg Apr. 22, 1952

